Experimental and Theoretical Studies of Unevenly Designed 4-bladed Inducers

由于H-II火箭的成功开发，日本在航空航天工程技术方面已经赶上了美国和欧洲。然而，在H-II、阿丽亚娜5号和航天飞机的涡轮泵诱导器的发展阶段观察到旋转空化现象。因此，旋转空化一直是世界范围内普遍存在的问题。在这种情况下，设计诱导器时既要考虑到更高的吸力性能，又要考虑到抑制旋转空化。本文制作了非均匀设计的四叶诱导体，从理论和实验两方面探讨了抑制或避免旋转空化的有效方法。(1)对叶片交替空化和旋转空化进行了理论分析。通过稳态分析发现，在一定的空化数范围内，均长空化和交替叶片空化都存在。在这种情况下，通过稳定性分析也发现，交替叶片空化比等长空化更稳定。此外，将这些分析扩展到非均匀设计的四叶诱导体情况，并对旋转空化和交替叶片空化的稳定性进行了检验。(2)按照LE-7的3叶诱导设计，制作了4叶诱导。本文还制作了另一种不带反掠的四叶诱导器，通过实验对比考察了反掠的效果。此外，还对不带后掠的诱导器进行了改进，每隔1个叶片进行轻度后掠的诱导器进行了试验。结果表明，后掠对旋转空化和交替叶片空化均有抑制作用。(3)通过混沌分析研究了进口压力波动的非线性行为，(1)的理论分析基于线性分析，(2)的实验主要采用傅立叶分析。本文探讨了通过观察相图中的吸引子来推导非定常空化信息的可能性。少

Owing to the successful development of the H-II Rocket, Japan has caught up with the U.S.A.and Europe in terms of the technology of aerospace engineering. Rotating cavitation, however, was observed in the development stage of the turbopump inducers for H-II,ARIANE V and Space Shuttle. So, the rotating cavitation has been a common problem all over the world. Under such conditions, inducers should be designed by taking into account the higher suction performance but also the suppression of the rotating cavitation. In this study, we manufactured unevenly designed 4-bladed inducers and investigated the effective ways to suppress or avoid the rotating cavitation both theoretically and experimentally.(1) Both the alternate blade cavitation and rotating cavitation were analyzed theoretically. By a steady analysis, it was found that both even length cavitation and alternate blade cavitation do exist in some range of cavitation number. In such a case, it was also found by a stability analysis t … More hat the alternate blade cavitation is more stable than even length cavitation. Moreover, these analyzes were extended for the case of unevenly designed 4-bladed inducers, and the stabilities of rotating cavitation and alternate blade cavitation were examined.(2)A 4-bladed inducer was manufactured along the same guideline with the designment of 3-bladed inducer for LE-7. Another 4-bladed inducer, which has no swept back, was also manufactured to examine the effect of swept back through the comparison of experiments. Moreover, an inducer with slightly swepted blades at 1 blade intervals, which were modified from the inducer without swept back, was tested. It was found that the swept back has an effect on the suppression of both rotating cavitation and alternate blade cavitation.(3) Non-linear behavior was investigated by chaotic analysis of inlet pressure fluctuation, whereas theoretical analyzes in (1) were based on linear analyzes, and mainlyFourier analysis was used in experiments in (2). We herein investigated the possibility to derive the information about the unsteady cavitation by the observation of attracters in the phase portrait. Less